What is the best DIY remedy for aphids ?

First spray the plants with the hose on a high enough spray to remove bugs but not damage the plants. Spray with a mix of water with a few drops of dish soap. Repeat often to keep the bugs away.

Spray them down with a horticultural oil and repeat as necessary.

Spray with dish soap and water (1 tsp soap to 1 quart water)then release lady bugs for control. You can buy them at the nursery or Home Depot. The lady bugs will eat the aphids.

Ditto what Patty S said

As for your other plants, can you tell if it's being eaten by bugs or critters? The oil will help for most bugs but you may have to take other steps if animals are eating your herbs.

When spraying the soapy water, make sure you get the under side of the leaves.